@jolduca/rehype-slug NPM

rehype-slug

rehype plugin to add ids to headings.

What is this?

This package is a unified (rehype) plugin to add ids to headings. It looks for headings (so <h1> through <h6>) that do not yet have ids and adds id attributes to them based on the text they contain. The algorithm that does this is github-slugger, which matches how GitHub works.

unified is a project that transforms content with abstract syntax trees (ASTs). rehype adds support for HTML to unified. hast is the HTML AST that rehype uses. This is a rehype plugin that adds ids to headings in the AST.

When should I use this?

This plugin is useful when you have relatively long documents and you want to be able to link to particular sections.

A different plugin, rehype-autolink-headings, adds links to these headings back to themselves, which is useful as it lets users more easily link to particular sections.

Install

This package is ESM only. In Node.js (version 12.20+, 14.14+, or 16.0+), install with npm:

npm install rehype-slug

In Deno with esm.sh:

import rehypeSlug from 'https://esm.sh/rehype-slug@5'

In browsers with esm.sh:

<script type="module">
  import rehypeSlug from 'https://esm.sh/rehype-slug@5?bundle'
</script>

Use

Say we have the following file example.html:

<h1 id=some-id>Lorem ipsum</h1>
<h2>Dolor sit amet 😪</h2>
<h3>consectetur &amp; adipisicing</h3>
<h4>elit</h4>
<h5>elit</h5>

And our module example.js looks as follows:

import {read} from 'to-vfile'
import {rehype} from 'rehype'
import rehypeSlug from 'rehype-slug'

main()

async function main() {
  const file = await rehype()
    .data('settings', {fragment: true})
    .use(rehypeSlug)
    .process(await read('example.html'))

  console.log(String(file))
}

Now, running node example.js yields:

<h1 id="some-id">Lorem ipsum</h1>
<h2 id="dolor-sit-amet-">Dolor sit amet 😪</h2>
<h3 id="consectetur--adipisicing">consectetur &#x26; adipisicing</h3>
<h4 id="elit">elit</h4>
<h5 id="elit-1">elit</h5>

API

This package exports no identifiers. The default export is rehypeSlug.

`unified().use(rehypeSlug)`

Add ids to headings. There are no options.

Types

This package is fully typed with TypeScript. There are no extra exported types.

Compatibility

Projects maintained by the unified collective are compatible with all maintained versions of Node.js. As of now, that is Node.js 12.20+, 14.14+, and 16.0+. Our projects sometimes work with older versions, but this is not guaranteed.

This plugin works with rehype-parse version 1+, rehype-stringify version 1+, rehype version 1+, and unified version 4+.

Security

Use of rehype-slug can open you up to a cross-site scripting (XSS) attack as it sets id attributes on headings, which causes what is known as “DOM clobbering”. Please use rehype-sanitize and see its Example: headings (DOM clobbering) for information on how to properly solve it.